I'm not sure exactly how the hardware side of DVDs/CDs work but when you burn something you can see a pattern burned onto the disk. I presume if you zoomed right in until you could see the difference between 1s and 0s then you could notice a difference.

I had a bit too much time on my hands today and was wondering...

Theoretically if this is the case, could you not create an ISO file with a series of bits to create patterns and shapes on the disk? Or am I being too simple?

That's a given but you could do so but there is no app that I know of that does so and to what purpose would the disc in question serve as those visible patterns would preclude any data on the disc.So it would only serve on only as visual art or just an other coaster( we've all burned enough of those )